Chair having a back rest and means for adjusting the inclination thereof

ABSTRACT

A pocket member is fixed or adapted to be fixed to the seat plate of a chair. A horizontal shaft is rotatably mounted in said pocket member. A bearing member and a pinion are corotationally mounted on said shaft. A holder is pivoted to said pocket member on a horizontal axis and connected or adapted to be connected to the back rest of said chair. A gear segment is carried by said holder and in mesh with said pinion. A nonrotatable ratchet ring is coaxial with said shaft and secured to said pocket member and carries internal teeth. Two symmetrically opposite locking pawls are pivoted to said bearing member on axes which are parallel to said shaft. Each of said locking pawls has a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one, direction, and the other of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in the opposite, and only in the opposite, direction. Spring means urge said locking pawls into engagement with said internal teeth. Two cam followers are provided, each of which is generally parallel to said shaft and carried by one of said locking pawls. A hand wheel is freely rotatably mounted on said shaft and provided with first cam faces which are adapted to engage said cam follower of that of said locking pawls which normally holds said bearing member against rotation in the direction in which the hand wheel is being rotated, and with two spaced apart second cam faces. An additional cam follower is carried by said bearing member and extends with a backlash between said second cam faces.

United States Patent 1191 Kratzer Jan. 16, 1973 [54] CHAIR HAVING A BACK REST AND MEANS FOR ADJUSTING THE INCLINATION THEREOF [75] Inventor: Walter Kratzer, Altheim, Austria [73] Assignee: Wiesner-Hager KG, Altheim, Austria 22 Filed: Oct. 14, 1971 21 Appl. No.: 189,353

[30] Foreign Application Priority Data Oct. 30, 1970 Austria ..A 9766/70 [52] US. Cl. .[16/145, 297/362, 297/366 [51] Int. Cl. ..E05d 11/10 [58] Field of Search ..l6/l45, 140; 297/362, 366, 297/367, 368, 369, 358; 79/527, 530

Primary Examiner-Bobby R. Gay Assistant ExaminerPeter A. Aschenbrenner Attorney-Kurt Kelman [5 ABSTRACT A pocket member is fixed or adapted to be fixed to the seat plate of a chair. A horizontal shaft is rotatably mounted in said pocket member. A bearing member and a pinion are corotationally mounted on said shaft. A holder is pivoted to said pocket member on a horizontal axis and connected or adapted to be connected to the back rest of said chair. A gear segment is carried by said holder and in mesh with said pinion. A nonrotatable ratchet ring is coaxial with said shaft and secured to said pocket member and carries internal teeth. Two symmetrically opposite locking pawls are pivoted to said bearing member on axes which are parallel to said shaft. Each of said locking pawls has a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one, direction, and the other of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in the opposite, and only in the opposite, direction. Spring means urge said locking pawls into engagement with said internal teeth. Two cam followers are provided, each of which is generally parallel to said shaft and carried by one of said locking pawls. A hand wheel is freely rotatably mounted on said shaft and provided with first cam faces which are adapted to engage said cam follower of that of said locking pawls which normally holds said bearing member against rotation in the direction in which the hand wheel is being rotated, and with two spaced apart second cam faces. An additional cam follower is carried by said bearing member and extends with a backlash between said second cam faces.

13 Claims, 4 Drawing Figures PATENTEDJAN 16 ms 3,710,418

SHEET 1 [IF 3 PATENTEDJAM 16 ms 3.710 418 sum 2 0F 3 CHAIR HAVING A BACK REST AND MEANS FOR ADJUSTING THE INCLINATION THEREOF This invention relates to a device for adjusting the inclination of the back rest of chairs, particularly of office chairs, which device comprisesa pocket member, which is firmly connected to the seat plate and in which a holder for the rest carrier is pivoted on a horizontal axis.

In known devices for adjusting the inclination of the back rest of office chairs, the rest carrier is clamped together with the holder in the pocket member. Clamp screws are provided in most cases for this purpose and hold the rest in its adjusted position. When. the clamp screws have been loosened, the holder together with the rest carrier is pivotally movable about a horizontal axis. In most cases, the rest carrier is slidably mounted in the holder and is thus adjustable in height. The tightening of the clamp screws will hold the rest carrier in the position to which it has been adjusted in height and inclination. All these designs have the disadvantage that the back rest can be adjusted only when it is under no load. It cannot be adjusted when a person is sitting on the chair because the rest carrier must be held by hand when the clamp is to be released. When a person desires to relax, e.g., after strenuous typing work, he or she may wish to incline the back rest rearwardly for a short time while remaining seated on the chair. The known devices for adjusting the back rests of office chairs do not permit of such relatively frequent adjustment.

Whereas devices for adjusting the back rests of chairs occupied by a person are known, e.g., for use with car seats, such devices cannot be used with office chairs because the devices require a relatively large space and are so designed that they can be made only of steel. A spiral spring ratchet mechanism isused in most of these known devices to hold the back rest in position. That ratchet mechanism has such a design that it must take up considerable forces in the axial direction so that it must be made of steel, as has been mentioned.

It is an object of the invention to avoid these disadvantages and to provide for the adjustment of the inclination of back rests a device which is particularly suitable for use with office chairs and can be made in a simple manner and in large quantities using plastics material.

In a device of the kind defined first hereinbefore, the invention accomplishes the above-mentioned object essentially in that the holder comprises in known manner a gear segment, which is in mesh with a pinion that is corotationally mounted on a shaft, a bearing member is corotationally mounted on said shaft, two symmetrically oppositely disposed locking pawls having toothed outer sides are mounted in said bearing member for pivotal movement in a plane that is normal to the shaft, a nonrotatable ratchet ring having internal teeth is coaxial with the shaft, the toothed sides of the pawls are spring-urged against said internal teeth, each pawl blocks the bearing member against a rotation in which the other pawl permits of a rotation of such bearing member, each pawl comprises a pin or the like, which is parallel to the shaft, a hand wheel is freely rotatably mounted on the shaft and operable to impart by cam faces of the hand wheel and by said pins or the like a pivotal movement against the spring force to that pawl which blocks the bearing member against rotation in the corresponding direction, and the bearing member carries an additional pin or the like, which extends with a backlash between two additional cam faces of the hand wheel. Because the bearing member is corotational with the shaft and the shaft is corotational with the pinion, which is in mesh with a holder that is pivoted on a horizontal axis, the rest carrier is held in its adjusted position since the bearing member is held against rotation by means of the locking pawls forced against the nonrotatable ratchet ring. The hand wheel must be rotated to disengage the lockingpawl which blocks the bearing member against rotation in the direction of rotation of the hand wheel. Now a cam face of the hand wheel can act on the pin of the bearing member to rotate thelatter. When the hand wheel is released after it has been rotated, the locking pawl will reengage and the rest will be held in its new position. The design provided according to the invention is such that the operation of the device does not give rise to particularly strong force's so that plastics material may be used in making the device.

To provide for a simple design, which is compatible with the material to be used, it is particularly desirable to use a polygonal shaft, on which the pinion and the bearing member are corotationally mounted.

Another desirable feature of the invention resides in that the ratchet ring is mounted on a disc or the like, which has an extension that is preferably square in cross-section and extends into a mating aperture of the pocket member and is formed with a through bore in which the bearing member is rotatably mounted. With this special design of the ratchet ring, the same can be nonrotatably secured to the pocket member with simple means. No difficulties are involved in the connection between the pocket member, which is made of metal, and the ratchet ring consisting of plastics material. The bearing member may also be made of plastics material and can bemounted in a simple manner in the square extension of the disc in this arrangement. If the square aperture in the pocket member is larger than the square which is circumscribed to the pinion, the assembling of the device will be particularly .easy because the pinion fitted on the shaft can be conveniently inserted into the pocket member through said square aperture. The mounting will be further facilitated if the pinion has a bearing extension, which is mounted in the pocket member.

To provide a design having a minimum space requirement, thebearing member has preferably two circular apertures for receiving the: complementary end portions of the locking pawls.

Inanother embodiment of the invention, the cam faces of the hand wheel are defined by a cross-shaped aperture. The wall faces defining the cross-shaped aperture form the cam faces for engaging the pins or the like, ,which are disposed at the corners of an isosceles triangle on the locking pawls and the bearing member.

Finally, the invention teaches to provide a common spring for urging the locking pawls outwardly. This permits of a simplification of the structure whereas an adverse affect on the functional reliability need not be feared.

An embodiment of the invention is shown by way of example on the accompanying drawings, in which FIG. 1 shows the device according .to the invention in a longitudinal sectional view taken through the pocket member,

FIG. 2 is an enlarged transverse sectional view taken on line II-II in FIG. 1.

FIG. 3 is a side elevation showing the device with the hand wheel removed and FIG. 4 is a view showing the underside of the hand wheel.

A pocket member 2 is welded to the seat plate 1 of an office chair. A holder 3 is pivoted in said pocket member on a horizontal axis 4. The holder 3 comprises a gear segment 5, which is in mesh with a pinion 6. A carrier 7 for the back rest of the chair is slidably mounted in the holder 3. A spring-loaded detent member 8 is provided and serves to fix the carrier 7 in the position to which it has been adjusted in height. The pinion 6 comprises a bearing extension 9 (FIG. 2), which is mounted in the pocket member 2. The pinion 6 is fitted on a hexagonal shaft 10, which carries a bearing member 11. The bearing member 11 is mounted in a square extension 12 of a disc, which carries a ratchet ring 13. The square extension of the disc for the ratchet ring 13 extends into a complementary aperture formed in the pocket member 2, and the ratchet ring 13 is thus nonrotatably held in said pocket member.

Two locking pawls 15 and 16 are mounted in respective circular apertures 14 of the bearing member 11 and have a toothed outer side each. A spring 17 urged the outer side of each locking pawl 15 and 16 against the internal teeth of the ratchet ring 13. Each locking pawl is provided with a pin 18, which is parallel to the shaft. Another pin 19 is carried by the bearing member 1 1. A hand wheel 20 is freely rotatably mounted on the shaft but is not removable therefrom and formed with cam faces 21, 22 for engaging the pins 18 of the pawls l6 and 15. To install the device, it is sufficient to secure the pinion, the bearing member 11 mounted in the disc for the ratchet ring 13, and the hand wheel 20 to the shaft, to insert said elements into the pocket member 2 through the square aperture therein, and to hold the elements in position by a circlip 23.

The pin 19 of the bearing member 11 extends between'two cam faces 24, 25 of the hand wheel 20. When the hand wheel is rotated, e.g., in a clockwise sense, the pin 18 of the locking pawl 16 will be engaged and driven by the cam face 22 so that the locking pawl 16 releases the bearing member 11 to rotate in the clockwise sense. This is so because the locking pawl prevents only a rotation in the clockwise sense and for this reason does not obstruct the present movement. After a rotation through an angle which is somewhat larger than required to disengage the locking pawl, the cam face 25 imparts a rotation to the pin 19 and by the bearing member 11 transmits the rotation to the shaft, the pinion and the holder 3 so that the inclination of the back rest is adjusted. When the back rest has reached the desired inclination, the hand wheel is released, the spring 17 forces the locking pawl 16 against the ratchet ring 13 having internal teeth, and the bearing member is again locked against rotation in both directions. When the hand wheel is rotated in a counterclockwise sense, the pawl 15 normally locking the bearing member against a rotation in this sense will be disengaged and the cam face 25 will impart a pivotal movement in the opposite direction to the bearing member and the back rest.

During a rotation of the hand wheel, no pawl which remains engaged such as the pawl 15 when the hand wheel is rotated in a clockwise sense should slip over the internal teeth of the ratchet ring. To prevent such slipping, another cam face 26 may be provided in the hand wheel. This cam face 26 is indicated in dash-dot lines in FIG. 4 and bears on the pin 19 to disengage the pawl so that both pawls are disengaged from the ratchet ring during a rotation of the hand wheel.

What is claimed is:

l. A device for adjusting the inclination of a back rest of a chair having a seat plate, which device comprises a pocket member adapted to be fixed to said seat plate,

a horizontal shaft rotatably mounted in said pocket member,

a bearing member corotationally mounted on said shaft,

a pinion corotationally mounted on said shaft,

a holder pivoted to said pocket member on a horizontal axis and adapted to be connected to said back rest,

a gear segment carried by said holder and in mesh with said pinion,

a nonrotatable ratchet ring which is coaxial with said shaft and secured to said pocket member and carries internal teeth,

two symmetrically opposite locking pawls pivoted to said bearing member on axes which are parallel to said shaft, each of said locking pawls having a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one,

direction, and the other of said locking pawls is engageable with said internal teeth to hold said hearing member and shaft against rotation in the opposite, and only in the opposite, direction,

spring means urging said locking pawls into engagement with said internal teeth,

two cam followers, each of which is generally parallel to said shaft and carried by one of said locking pawls,

a hand wheel, which is freely rotatably mounted on said shaft and provided with first cam faces which are adapted to engage said cam follower of that of said locking pawls which normally holds said hearing member against rotation in the direction in which the hand wheel is being rotated, and with two spaced apart second cam faces, and an additional cam follower carried by said bearing member and extending with a backlash between said second cam faces. 2. A device as set forth in claim 1, in which said cam followers carried by said locking pawls consist of pins.

3. A device as set forth in claim 1, in which said additional cam follower consists of a pin.

4. A device as set forth in claim 1, in which said shaft is polygonal and said pinion and said bearing member have polygonal apertures which are complementary to and receive said polygonal shaft. 5. A device as set forth in claim 1, in which said ratchet ring is carried by a ring carrier having an extension formed with a through bore, said pocket member is formed with an aperture which mates and receives said extension, and said bearing member is rotatably mounted in said through bore. 6. A device as set forth in claim 1, in which said ring carrier consists of a disc.

7. A device as set forth in claim 5, in which said extension and said aperture in said pocket member are square.

8. A device as set forth in claim 7, in which said square aperture in said pocket member is larger than an imaginary square circumscribed to said pinion.

9. Apparatus as set forth in claim 1, in which said pinion has a bearing extension, which is rotatably mounted in said pocket member.

10. A device as set forth in claim 1, in which said bearing member has two circular apertures and said locking pawls have end portions which are complementary to and received in said circular apertures.

11. A device as set forth in claim 1, in which said hand wheel is formed with a cross-shaped aperture which is partly defined by said first and second cam faces.

12. A device as set forth in claim 1, in which said spring means consist of a single spring urging said locking pawls toward said internal teeth.

13. In a chair having a seat plate, a back rest, and a back rest carrier rigid with said back rest,

the provision of a device for adjusting the inclination of said back rest, which device comprises:

a pocket member fixed to said seat plate,

a horizontal shaft rotatably mounted in said pocket member,

a bearing member corotationally mounted on said shaft,

a pinion corotationally mounted on said shaft,

a holder pivoted to said pocket member on a horizontal axis and connected to said back rest carrier,

, a gear segment carried by said holder and in mesh with said pinion,

a nonrotatable ratchet ring which is coaxial with said shaft and secured to said pocket member and carries internal teeth,

two symmetrically opposite locking pawls pivoted to said bearing member on axes which are parallel to said shaft, each of said locking pawls having a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one, direction, and the other of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in the opposite, and only in the opposite, direction,

spring means urging said locking pawls into engagement with said internal teeth, two cam followers, each of which 18 generally parallel 

1. A device for adjusting the inclination of a back rest of a chair having a seat plate, which device comprises a pocket member adapted to be fixed to said seat plate, a horizontal shaft rotatably mounted in said pocket member, a bearing member corotationally mounted on said shaft, a pinion corotationally mounted on said shaft, a holder pivoted to said pocket member on a horizontal axis and adapted to be connected to said back rest, a gear segment carried by said holder and in mesh with said pinion, a nonrotatable ratchet ring which is coaxial with said shaft and secured to said pocket member and carries internal teeth, two symmetrically opposite locking pawls pivoted to said bearing member on axes which are parallel to said shaft, each of said locking pawls having a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one, direction, and the other of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in the opposite, and only in the opposite, direction, spring means urging said locking pawls into engagement with said internal teeth, two cam followers, each of which is generally parallel to said shaft and carried by one of said locking pawls, a hand wheel, which is freely rotatably mounted on said shaft and provided with first cam faces which are adapted to engage said cam follower of that of said locking pawls which normally holds said bearing member against rotation in the direction in which the hand wheel is being rotated, and with two spaced apart second cam faces, and an additional cam follower carried by said bearing member and extending with a backlash between said second cam faces.
 2. A device as set forth in claim 1, in which said cam followers carried by said locking pawls consist of pins.
 3. A device as set forth in claim 1, in which said additional cam follower consists of a pin.
 4. A device as set forth in claim 1, in which said shaft is polygonal and said pinion and said bearing member have polygonal apertures which are complementary to and receive said polygonal shaft.
 5. A device as set forth in claim 1, in which said ratchet ring is carried by a ring carrier having an extension formed with a through bore, said pocket member is formed with an aperture which mates and receives said extension, and said bearing member is rotatably mounted in said through bore.
 6. A device as set forth in claim 1, in which said ring carrier consists of a disc.
 7. A device as set forth in claim 5, in which said extension and said aperture in said pocket member are square.
 8. A device as set forth in claim 7, in which said square aperture in said pocket member is larger than an imaginary squaRe circumscribed to said pinion.
 9. Apparatus as set forth in claim 1, in which said pinion has a bearing extension, which is rotatably mounted in said pocket member.
 10. A device as set forth in claim 1, in which said bearing member has two circular apertures and said locking pawls have end portions which are complementary to and received in said circular apertures.
 11. A device as set forth in claim 1, in which said hand wheel is formed with a cross-shaped aperture which is partly defined by said first and second cam faces.
 12. A device as set forth in claim 1, in which said spring means consist of a single spring urging said locking pawls toward said internal teeth.
 13. In a chair having a seat plate, a back rest, and a back rest carrier rigid with said back rest, the provision of a device for adjusting the inclination of said back rest, which device comprises: a pocket member fixed to said seat plate, a horizontal shaft rotatably mounted in said pocket member, a bearing member corotationally mounted on said shaft, a pinion corotationally mounted on said shaft, a holder pivoted to said pocket member on a horizontal axis and connected to said back rest carrier, a gear segment carried by said holder and in mesh with said pinion, a nonrotatable ratchet ring which is coaxial with said shaft and secured to said pocket member and carries internal teeth, two symmetrically opposite locking pawls pivoted to said bearing member on axes which are parallel to said shaft, each of said locking pawls having a toothed outer side which faces said internal teeth and is engageable therewith in such a manner that one of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in one, and only one, direction, and the other of said locking pawls is engageable with said internal teeth to hold said bearing member and shaft against rotation in the opposite, and only in the opposite, direction, spring means urging said locking pawls into engagement with said internal teeth, two cam followers, each of which is generally parallel to said shaft and carried by one of said locking pawls, a hand wheel, which is freely rotatably mounted on said shaft and provided with first cam faces which are adapted to engage said cam follower of that of said locking pawls which normally holds said bearing member against rotation in the direction in which the hand wheel is being rotated, and with two spaced apart second cam faces, and an additional cam follower carried by said bearing member and extending with a backlash between said second cam faces. 